The present invention relates to the improvement of an internal combustion engine which is powered by converting the reciprocating motion of a piston to rotating motion.
In such type of an internal combustion engine with the reciprocating piston there is generally provided a predetermined piston clearance between the piston and the inner wall of the cylinder. Because thermal expansion of the piston, which is especially made of aluminum alloy, is greater than the cylinder, it is necessary to provide a large piston clearance. Therefore, the piston swings about the piston pin within the piston clearance when the moving direction of the piston is reversed at the stroke ends. This means that the periphery of the piston strikes the inner wall of the cylinder to make a slapping noise.